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(No Model.)

O. E. SGRIBNER. ANNUNOIATOR FOR TELEPHONE LINES.

No. 596,627. Patented Jan. 4, 1898.

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UNITED STATES PATENT OFFICE.

- CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE IVESTERNELECTRIC COMPANY, OF SAME PLACE.

ANNUNCIATOR FOR TELEPHONE-LINES.

SPECIFICATION forming part of Letters Patent No. 596,627, dated January4, 1898.

Application filed May 14,1896- Serial No. 591,52 l. (No model.)

To all whom it may concern.-

Be it known that 1, CHARLES E. ScRIBNER, a citizen of the United States,residing at Chicago, in the county of Cook and'State of Illinois, haveinvented a certain new and useful Improvement in Annunciators forTelephone- Lines, (Case No. 421,) of which the following is a full,clear, concise, and exact description, reference being had to theaccompanying drawings, forminga part of this specification.

My invention applies to telephone -lines equipped with line-annunciatorsand with means for making connection with the lines in atelephone-switchboard and with generators of signaling-current atthesubstations for causing the display of the line-annunciators.

The purpose of the invention is to provide means for causing thecontinued displayof the annunciator after the transmission of amomentary signaling-current through it and for effacing the signal orconcealing the indicator of the annunciator when connection is made withthe line. To this end I have provided a signaling instrument orannunciator constructed to displayits indicator when excited by currentin its magnet-coil, an electromagnetically actuated switch responsive tothe calling-current, switch-contacts in the spring-jack orconnection-socket of the line, which are separated when connection ismade with the line, and a system of circuits unit in g this apparatussuch that the transmission of a momentary signaling-current from thesubstation causes the display of the indicator and at the sametimecloses a circuit of a local source of current through theannunciator to insure its continuous excitement, and that the insertionof a connecting-plug in the spring-jack to make connection with the lineinterrupts the current from the local source and permits the return ofthe annunciator and of the switch to their normal positions.

In practice I prefer that theelectromagnetically-operatedswitch-contacts should be controlled by the armature of the annunciatoritself, thus dispensing with unnecessary mechanism.

In a commercial form of the invention the electromagnet of theannunciator is provided with an armature which when attracted 0p eratesa shutter or indicator and simultaneously closes a pair ofswitch-contacts. This annunciator is included in a bridge of theline-circuit, which may be interrupted at the switch-contacts of theusual spring-jack in the switchboard, together with a resistancecoil,which should preferably be interposed in the circuit between equalportions of the winding of the magnet, the magnet being divided into twoequal helices for this purpose.

In a conductor controlled by the switch-contacts of the annunciator andconnected in shunt or parallel circuit with the resistancecoil is placeda local battery or other source of current.

In the normal condition of this apparatus the circuit of the localsource of current is interrupted at the switch-contacts of theannunciator, while the line connection with the annunciator is closed inthe spring jack. When a momentary calling-current is transmitted in theline from the substation-as, for example, by means of the usualmagnetogeneratorthe armature of the annunciator is attracted, displayingor actuating the i11- dicator of the instrument and also closing thecircuit of the local battery. After the cessation of the calling-currenta current still flows through the annunciator to the line from the localsource of current, which maintains the excitement of the annunciator andeffects the continueddisplay of its indicator. When,'h0wever, a plug isinserted into the spring-jack of the line in response to a call, thiscurrent from the local source is interrupted and the annunciatorrestored to its normal inert condition.

Thus by the use of well-known apparatus of very simple and inexpensiveconstruction I am enabled to obtain substantially the same results ashave heretofore been reached with the aid of complicated mechanism andinvolved circuits.

Of the accompanying drawings illustrative of the invention, Figure 1 isa diagram of the circuits which constitute the invention in combinationwith well-known apparatus of telephone-switchboards. The apparatus of asingle substation is represented connected Ioo through line-wires with aspring-jack and an annunciator in the switchboard. Fig. 2 is anelevation of a form of annunciator which I have found suitable for usein the system.

The apparatus at the substation may comprise a polarized signal-bell aand a generator of signaling-current a, permanently connected in theline-circuit, a receiving-telephone a transmitting-telephone a and aswitch a for closing the line-circuit through these telephonicinstruments when the telephone is brought into position for use. Theline-wires 1 and 2 are connected in the switchboard with theswitch-springs b and b of a spring-jack c, from which they are normallyextended, through the medium of the contact-anvils of the spring-jack,to the terminals of the line-annunciator d. The magneti'zing-coil ofthis annunciator is constructed in two separate windings, whose innerterminals are connected together through a resistance-coil e.

The annunciator, as shown in Fig 2, has a tubular electromagnet cl, anarmature d pivoted at its lower edge, a shutter or shield d hung onbrackets carried by the armature and normally-concealing its face, and afixed stud or pin 61 which impinges upon the shield below its pivotalpoint when the armature moves toward the magnet. The pivots or trunnionsof the armature d are carried in brackets fixed to the shell of thetubular magnet. The pin (1 is likewise carried by a bracket secured tothe shell, but is insulated from the other parts of the apparatus by abushing surrounding the pin.

While the magnet is inert the armature d falls outward to a slightdistance. The shield (1 depends in front of the armature and concealsit. When the magnet becomes excited and the armature is attracted to it,the shield 61 strikes the projecting extremity of the pin d and isthrust into a horizontal position, sliding or rolling over the curvedextremity of the pin. As soon as the exciting-current in the magnet isinterrupted the armature falls outward and permits the shield to returnto its first position.

In the switchboard the frame or armature d of the annunciator isconnected by a wire 3 with one terminal of the resistance-coil e, whilethe pin 01 is connected by another condoctor at with the other terminalof the same coil, a battery f or other generator of current beinginterposed in this wire.

The function of the resistance-coil e is to provide a circuit throughwhich the signalingcurrent for operating the annunciator may betransmitted, while at the same time serving to divert current from thebattery f, which is in parallel circuit with it, through the windings ofthe annunciator. When the circuit 3 4 is closed, the resistance-coil 6produces a sufficient difference of potential between its terminals asrespects the current from battery f to produce a flow of current throughthe windings of the annunciator.

In sending a call from the substation to the central station by means ofthis apparatus the subscriber operates his generator or as usual,producing for a short time an alternating current in the line 1 2,whichfinds circuit through the spring-jack 0, through the two windings of theannunciator d, and through the resistance-coil e. The magnet of theannunciator is excited by this current and attracts its armature,bringing the shield d into' contact with the pin 01*, thus throwing theshutter into position to disclose the face of the armature and at thesame time to complete the connection of battery f with the line. Whenthe circuit of the battery is thus closed, a current therefrom .fiowsthrough wire 4 to wire 3, thence through one winding of the annunciatorto line conductor 2, through the apparatus at the substation, returningby line conductor 1, traversing the other winding of theannunciator-magnet, and thence finding its return to battery f. Thiscurrent continues to flow after the operation of the generator a hasceased and holds the shutter of the armature in its raised position. Inresponse to this signal the operator may insert the usualconnecting-plug g into the spring-jack c of the line, whereby theconnection of theannunciator with the line is broken. The breaking ofthis circuit interrupts the current from battery f, the magnet of theannunciator loses its magnetization, and the shutter falls into itsnormal position, concealing the face of the armature. The annu nciatoris thus automatically restored in the act of inserting a plug into thespring-jack.

Any of several well-known types of annunciator or visible signal may beused in place of the one herein described. Several minor variations inthe circuit may also be made without departing from the mode ofoperation which constitutes the essence of my i11- vention.

I claim as new and desire to secure by Letters Patent 1. The combinationwith a closed signalingcircuit, of an annunciator having its windingtogether with a resistance-coil in the signaling-circuit, a source ofcurrent in a normally open shunt about the resistance-coil,switchcontacts in the annunciator actuated by the excitement thereof toclose the said shunt and a switch adapted to break the circuit of thebattery through the annunciator as described.

2. The combination with a telephone-line having at its substation meansfor producing in the line a momentary signaling-current, and at acentral station an annunciator in the line-circuit and a spring-jackconnected with the line, of switch-contacts controlled by anelectromagnet responsive to such momentary signaling-currents, a localsource of current, circuit connections controlled by the switchcontactsadapted to bring the local source of current into circuit with theannunciator, and other switch-contacts in the spring-jack adapted tointerrupt the circuit of said local source of current when a plug isinserted into the spring-jack, substantially as described.

3. The combination with a telephone-line having a generator of momentarysignalingcurrent at its substation, and an annunciator and a spring-jackswitch in the line at the central station, of switch-contacts controlledby the armature of the annunciator, a local source of current andcircuit connections including said switch-contacts adapted to bring saidlocal source of current into the line-circuit when the switch-contactsare closed, whereby the indicator of the annunciator is displayed whenthe substation-generator is operated and remains displayed until a-plugis inserted in the spring-jack, as described.

4. The combination with a telephone-line having at its substation agenerator of signaling-current and at its central station a spring-CHARLES E. SCRIBNER.

Witnesses ELLA EDLER, LUCILE RUSSELL.

